This invention is in the field of corn breeding, specifically relating to an inbred corn line designated ZS02338.
The original maize plant was indigenous to the Western Hemisphere. The plants were weedlike and only through the efforts of early breeders was a cultivated crop species developed. The physical traits of maize are such that self pollination or cross pollination can occur. Each plant has a separate male and female flower, the tassel and ear, respectively. Natural pollination occurs when wind transfers pollen from tassel to the silks on the corn ears. This type of pollination contributed to the wide variation of maize varieties present in the Western Hemisphere.
The development of a planned breeding program for maize only occurred in the last century. Originally, maize was an open pollinated variety having heterogeneous genotypes. The maize farmer selected uniform ears from the yield of these genotypes and reserved them for planting the next season. The result was a field of maize plants that were segregating for a variety of traits. This type of maize selection lead to at most incremental increases in seed yield.
Large increases in seed yield were the result of the development of hybrid corn varieties in planned breeding programs. Hybrids were developed by selecting corn lines and selfing these lines for several generations to develop homozygous pure inbred lines and crossing selected inbred lines with unrelated inbred lines to produce hybrid progeny (F1). Inbred lines can be difficult to produce since the inbreeding process in corn decreases the vigor. However, when two inbred lines are crossed, the hybrid plant evidences greatly increased vigor compared to open pollinated segregating maize plants. An important factor of the homozygosity and the homogeneity of the inbred lines is that the hybrid from any cross will always be the same, and can be reproduced.
The ultimate objective of the commercial maize seed companies is to produce high yielding, agronomically sound plants which perform well in certain regions or areas of the Corn Belt. To produce these types of hybrids, the companies must develop inbreds which carry needed traits into the hybrid combination. Hybrids are not uniformly adapted for the Corn Belt, but are specifically adapted for regions of the Corn Belt. Northern regions of the Corn Belt require shorter season hybrids than do southern regions of the Corn Belt. Hybrids that grow well in Colorado and Nebraska soils may not flourish in rich Illinois soil. Thus, a variety of major agronomic traits are important in hybrid combination for the various Corn Belt regions, and have an impact on hybrid performance.
Inbred line development and hybrid testing have been emphasized in the past half century in commercial maize production as a means to increase hybrid performance. Inbred development is usually done by pedigree selection. Pedigree selection can be selection in an F2 population produced from a planned cross of two genotypes (often elite inbred lines), or selection of progeny of synthetic varieties, open pollinated, composite, or backcross populations. This type of selection is effective for highly inheritable traits, but other traits, for example, yield requires replicated test crosses at a variety of stages for accurate selection.
Maize breeders select for a variety of traits in inbreds that impact hybrid performance along with selecting for acceptable parental traits. Such traits include yield potential in hybrid combination; dry down; maturity; grain moisture at harvest; greensnap; resistance to root lodging; resistance to stalk lodging; grain quality; disease and insect resistance; ear and plant height; performance in different soil types such as: low level of organic matter, clay, sand, black, high pH, low pH; performance in: wet environments, drought environments, and no tillage conditions. These traits appear to be governed by a complex genetic system that makes selection and breeding of an inbred line extremely difficult. Even if an inbred, in hybrid combination, has excellent yield (a desired characteristic), it may not be useful because it fails to have acceptable parental traits such as seed yield, seed size, pollen production, good silks, plant height, etc.
To illustrate the difficulty of breeding and developing inbred lines, the following example is given. Two inbreds compared for similarity of 29 traits differed significantly for 18 traits between the two lines. If 18 simply inherited single gene traits were polymorphic with gene frequencies of 0.5 in the parental lines, and assuming independent segregation (as would essentially be the case if each trait resided on a different chromosome arm), then the specific combination of these traits as embodied in an inbred would only be expected to become fixed at a rate of one in 262,144 possible homozygous genetic combinations. Selection of the specific inbred combination is also influenced by the specific selection environment on many of these 18 traits which makes the probability of obtaining this one inbred even more remote. Thus, the general procedure of producing a non segregating F1 generation and self pollinating to produce a F2 generation that segregates for traits does not easily lead to a useful inbred. Great care and breeder expertise must be used in selection of breeding material to continue to increase yield and agronomics of inbreds and resultant commercial hybrids.
The present invention relates to an inbred corn line ZS02338. Specifically, this invention relates to plants and seeds of this line. Additionally, this relates to a method of producing hybrid seed corn from this inbred. More particularly, this invention relates to the unique combination of traits in corn line ZS02338.
Generally then, the present invention includes an inbred corn seed designated ZS02338. This seed produces a corn plant.
The invention also includes the tissue culture of regenerable cells of ZS02338 wherein the tissue regenerates plants having the genotype of ZS02338. The tissue culture is selected from the group consisting of leaves, pollen, embryos, roots, root tips, anthers, silk, flowers, kernels, ears, cobs, husks and stalks, and cells and protoplasts thereof. The corn plant regenerated from ZS02338 having ZS02338""s genotype.
The invention extends to hybrid seed produced by planting, in pollinating proximity, seeds of corn inbred lines ZS02338 and another inbred line; cultivating corn plants resulting from said planting; preventing pollen production by the plants of one of the inbred lines; allowing natural cross pollinating to occur between said inbred lines; and harvesting seeds produced on plants of the inbred. The hybrid seed produced by hybrid combination of plants of inbred corn seed designated ZS02338 and plants of another inbred line. Hybrid plants grown from this hybrid seed.
The invention further includes a method of hybrid F1 production. A first generation (F1) hybrid corn plant produced by the process of planting, in pollinating proximity, seeds of corn inbred lines ZS02338 and another inbred line; cultivating corn plants resulting from said planting; preventing pollen production by the plants of one of the inbred lines; allowing natural cross pollinating to occur between said inbred lines; harvesting seeds produced on plants of the inbred; and growing a harvested seed.
A tissue culture of the regenerable cells of hybrid plants produced with use of ZS02338 genetic material. A tissue culture of the regenerable cells of the corn plant produced by the method described above.
In the description and examples which follow, a number of terms are used. In order to provide a clear and consistent understanding of the specifications and claims, including the scope to be given such terms, the following definitions are provided.
BL MOIST
The moisture percentage of the grain at black layer, i.e., when 50% of the plants per plot have reached physiological maturity.
COLD GERM
Cold Germ is a measurement of seed germination under cold soil conditions. Data is reported as percent of seed germinating.
ECB
European corn borer a maize eating insect. ECBI is the first brood generation of European corn borers. ECBII is the second generation of European corn borers.
EMERGE
The number of emerged plants per plot (planted at the same seedling rate) collected when plants have two fully developed leaves.
GI
This is a selection index which provides a single quantitative measure of the worth of a hybrid based on four traits. Yield is the primary trait contributing to index values. The GI value is calculated by combining stalk lodging, root lodging, yield and dropped ears according to the attached mathematical formula:
GI=100+0.5 (YLD)xe2x88x920.9(% STALK LODGE)xe2x88x920.9(% ROOT LODGE)xe2x88x922.7(% DROPPED EAR) 
GLS
Gray Leaf Spot (Cercospora Zeae) disease rating. This is rated on a 1-9 scale with a xe2x80x9c1xe2x80x9d being very susceptible, and a xe2x80x9c9xe2x80x9d being very resistant.*
GW
Goss"" Wilt (Corynebacterium nebraskense). This is rated on a 1-9 scale with a xe2x80x9c1xe2x80x9d being very susceptible, and a xe2x80x9c9xe2x80x9d being very resistant.*
HEATP10
The number of Growing Degree Units (GDU""s) or heat units required for an inbred line or hybrid to have approximately 10 percent of the plants shedding pollen. This trait is measured from the time of planting. Growing Degree Units are calculated by the Barger Method where the GDU""s for a 24 hour period are:   GDU  =                    (                              Max            ⁢                          xe2x80x83                        ⁢            Temp            ⁢                          xe2x80x83                        ⁢                          (                              xc2x0F                .                            )                                +                      Min            ⁢                          xe2x80x83                        ⁢            Temp            ⁢                          xe2x80x83                        ⁢                          (                              xc2x0F                .                            )                                      )            2        -    50  
The highest maximum temperature used is 86xc2x0 F. and the lowest minimum temperature used is 50xc2x0 F. For each inbred or hybrid it takes a certain number of GDU""s to reach various stages of plant development.
HEATBL
The number of GDU""s after planting when approximately 50 percent of the inbred or hybrid plants in a plot have grain which has reached physiological maturity (black layer).
HEATPEEK
The number of GDU""s after planting of an inbred when approximately 50 percent of the plants show visible tassel extension.
HEATP50 or HTP50
The number of GDU""s required for an inbred or hybrid to have approximately 50 percent of the plants shedding pollen. Growing Degree Units are calculated by the Barger Method as shown in the HEATP10 definition.
HEATP90
The number of GDU""s accumulated from planting when the last 100 percent of plants in an inbred or hybrid are still shedding enough viable pollen for pollination to occur. Growing Degree Units are calculated by the Barger Method as shown in the HEATP10 definition.
HEATS10
The number of GDU""s required for an inbred or hybrid to have approximately 10 percent of the plants with silk emergence of at least 0.5 inches. Growing Degree Units are calculated by the Barger Method as shown in the HEATP10 definition.
HEATS50 or HTS50
The number of GDU""s required for an inbred or hybrid to have approximately 50 percent of the plants with silk emergence of at least 0.5 inches. Growing Degree Units are calculated by the Barger Method as shown in the HEATP10 definition.
HEATS90
The number of GDU""s required for an inbred or hybrid to have approximately 90 percent of the plants with silk emergence of at least 0.5 inches. Growing Degree Units are calculated by the Barger Method as shown in the HEATP10 definition.
MDMVA 
Maize Dwarf Mosaic Virus strain A. The corn is rated on a 1-9 scale with a xe2x80x9c1xe2x80x9d being very susceptible, and a xe2x80x9c9xe2x80x9d being very resistant.*
MDMVB 
Maize Dwarf Mosaic Virus strain B. This is rated on a 1-9 scale with a xe2x80x9c1xe2x80x9d being very susceptible and a xe2x80x9c9xe2x80x9d being very resistant.*
MOISTURE
The average percentage grain moisture of an inbred or hybrid at harvest time.
NLB
Northern Leaf Blight (Exserohilum turcicum) disease rating. This is rated on a 1-9 scale with a xe2x80x9c1xe2x80x9d being very susceptible, and a xe2x80x9c9xe2x80x9d being very resistant.*
PCT TILLER
The total number of tillers per plot divided by the total number of plants per plot.
PLANT
This term includes plant cells, plant protoplasts, plant cell tissue cultures from which corn plants can be regenerated, plant calli, plant clumps, and plant cells that are intact in plants or parts of plants, such as embryos, pollen, flowers, kernels, ears, cobs, leaves, husks, stalks, roots, root tips, anthers, silk and the like.
PLANT HEIGHT
The distance in centimeters from ground level to the base of the tassel peduncle.
RM
Predicted relative maturity based on the moisture percentage of the grain at harvest. This rating is based on known set of checks and utilizes standard linear regression analyses and is referred to as the Minnesota Relative Maturity Rating System.
SHED
The volume of pollen shed by the male flower rated on a 1-9 scale where a xe2x80x9c1xe2x80x9d is a very light pollen shedder, a xe2x80x9c4.5xe2x80x9d is a moderate shedder, and a xe2x80x9c9xe2x80x9d is a very heavy shedder.
SLB
Southern Leaf Blight (Bipolaris maydis) disease rating. This is rated on a 1-9 scale with a xe2x80x9c1xe2x80x9d being very susceptible, and a xe2x80x9c9xe2x80x9d being very resistant.*
TWT
The measure of the weight of grain in pounds for a one bushel volume adjusted for percent grain moisture.
VIGOR
Visual rating of 1 to 9 made 2-3 weeks post-emergence where a xe2x80x9c1xe2x80x9d indicates very poor early plant development, and a xe2x80x9c9xe2x80x9d indicates superior plant development.
WARM GERM
A measurement of seed germination under ideal (warm, moist) conditions. Data is reported as percent of seeds germinating.
YIELD (YLD)
Actual yield of grain at harvest adjusted to 15.5% moisture. Measurements are reported in bushels per acre.
% DROPPED EARS (DE)
The number of plants per plot which dropped their primary ear divided by the total number of plants per plot.
% LRG FLAT
Percentage by weight of shelled corn that passes through a {fraction (26/64)} inch round screen and a {fraction (14/64)} inch slot screen, but does not pass through a screen with {fraction (20.5/64)} inch round openings.
% LRG ROUND
Percentage by weight of shelled corn that passes through a {fraction (26/64)} inch round screen, but does not pass through a {fraction (14/64)} inch slot screen or a screen with {fraction (20.5/64)} inch round openings.
% MED FLAT
Percentage by weight of shelled corn that passes through a {fraction (20.5/64)} inch round screen and a {fraction (13/64)} inch slotted screen, but does not pass through a screen with {fraction (17/64)} inch round openings.
% MED ROUND
Percentage by weight of shelled corn that passes through a {fraction (20.5/64)} inch round screen, but does not pass through a {fraction (13/64)} inch slot screen or a screen with {fraction (17/64)} inch round openings.
% SML FLAT
Percentage by weight of shelled corn that passes through a {fraction (17/64)} inch round screen and a {fraction (12/64)} inch slotted screen, but does not pass through a screen with {fraction (15/64)} inch round openings.
% SML ROUND
Percentage by weight of shelled corn that passes through a {fraction (17/64)} inch round screen, but does not pass through a {fraction (12/64)} inch slotted screen or a screen with {fraction (15/64)} inch round openings.
% ROOT LODGE (RL)
Percentage of plants per plot leaning more that 30 degrees from vertical divided by total plants per plot.
% STALK LODGE (SL)
Percentage of plants per plot with the stalk broken below the primary ear node divided by the total plants per plot.
* Resistantxe2x80x94on a scale of 1-9 with 9 evidencing the trait most strongly: 1-2.9 ratings are susceptible, 3-5.9 ratings are intermediate, and 6-9 ratings are resistant.